The present invention is related to gas treatment of products, specifically food and similar products, using gas jets which impinge upon the products for e.g. cooling, heating or drying them.
Devices for cooling or heating food products are known from e.g. U.S. Pat. No. 4,679,542 to Donald P. Smith et al. These devices comprise a housing in which a high-pressure gas plenum communicates with upper and lower ducts defining a treatment area therebetween and having a plurality of nozzles for ejecting gas jets vertically into the treatment area. The food products to be treated are supported by a conveyor belt that transports them through the treatment area.
The design of these known devices is quite complex, resulting in difficulties in meeting the high hygienic requirements of the food industry. Also, the maintenance of the prior art devices is time-consuming, and the intervals between successive shutdowns are short.
Another apparatus for cooling, heating or drying of products is known from U.S. Pat. No. 5,408,921 to Per-Oskar Persson et al. This apparatus comprises a housing and a conveyor belt for transporting the products through the housing along a path from an inlet opening to an outlet opening in the housing. A tunnel encloses the conveyor belt at least along a part of the path from the inlet opening to the outlet opening. Cold air is circulated by fan means through perforations in the tunnel walls opposite to the products carried on the conveyor belt such that air jets impinge upon the surface of the products, and further out of the tunnel to air conditioning means for conditioning the air and then back to the outside of the tunnel.
This prior art apparatus substantially eliminates or at least reduces the above-noted problems of the devices known from e.g. U.S. Pat. No. 4,679,542 to Donald P. Smith et al.
However, the known devices and apparatus are relatively bulky.